In recent years, an organic electroluminescence element, especially emitting white light, has become more efficient, and thus has been highly expected as a light source for the next generation which can replace a fluorescent being an existing major illumination lamp, or as a new illumination lamp for the next generation which could not be embodied by an existing light source.
However, if the organic electroluminescence element is used as illumination purpose, the efficiency is still insufficient. Thus, making higher efficient is required and becomes an issue.
In order to solve such an issue, there has been a development for efficiently extracting light emitted from the organic electroluminescence element. For example, an organic electroluminescence element having a transparent substrate is proposed in Japanese Patent Application Laid-Open No. 10-208875, and the transparent substrate is formed into a convex shape and is located with respect to each emission unit, and thereby the emitted light can be extracted more efficiently. However, total reflection at an interface between air and the substrate can not be prevented only by forming the substrate into the convex shape. Therefore, the above organic electroluminescence element can not obtain sufficient luminance efficiency as illumination purpose.
Also, a method for utilizing efficiently light emitted form an organic electroluminescence element is proposed in Japanese Patent Application Laid-Open No. 2004-39500. The organic electroluminescence element is provided in the side of its light-emitting surface with a microlens, and thereby the emitted light can be utilized efficiently. In this method, although light emitted in a center part of the microlens can be extracted efficiently, light emitted in the remaining part of the microlens can not be extracted due to total reflection at an interface between air and a surface of the microlens. As a result, making higher efficient has become an issue.